The invention relates to a circuit arrangement for synchronizing a type carrier with the count of a binary counter provided in a control unit in printers wherein the type carrier is set by a stepping motor advanced by means of stepping pulses. A sampling device is provided which produces a synchronizing signal whenever the type carrier assumes a predetermined position.
U.S. Pat. No. 4,005,264 discloses an arrangement for scanning a disc-shaped type carrier in printers, wherein the type carrier is set with the aid of a stepping motor. The arrangement contains a stepping motor control unit which is provided with a ring counter at the outputs of which drive pulses for the stepping motor are emitted. The ring counter is advanced by stepping pulse trains. The arrangement contains a comparator device which compares the binary values of the output pulses with binary values assigned to a specific character. In the event of identity, the comparator device emits an output pulse. The type carrier is provided with a scan sector which extends over a plurality of characters and comprises the specific character, for example the letter "E". Scan sectors are discussed in more detail in U.S. Pat. No. 4,005,264 incorporated herein by reference. When a scanning pulse occurs produced by means of a scanning element due to the scanning of the scan sector, and at the same time the comparator device produces the output pulse, the arrangement emits a synchronizing signal. This synchronizing signal is used to synchronize the position of the type carrier with a binary counter indicating the position of the type carrier.
U.S. Pat. No. 3,823,265, incorporated herein by reference, discloses a code-controlled printer, wherein the instantaneous position of the type carrier is caused to conform with the count of a binary counter arranged in a control unit of the printer in that a pulse train disc connected to the type carrier is provided with a synchronizing mark which is assigned to a frequently occurring, predetermined character, for example the letter "E". Independently of other settings, the binary counter is set to the code character assigned to this predetermined character, by means of a synchronizing signal, as soon as the synchronizing mark is recognized by an associated scanning element. Thus in this known printer, synchronization is carried out by the type carrier. In various situations, however, it is expedient not to synchronize the binary counter by the type carrier, but to synchronize the type carrier by the binary counter.